When Braves manager Fredi Gonzalez was weighing whether to keep Evan Gattis in the lineup Friday by playing him at first base, a position the rookie catcher had barely played in pro ball and not in nearly two years, Gonzalez employed a baseball adage he’s used before.

“I know that he’s going to get four at-bats,” Gonzalez said. “We don’t know that he’s going to get four ground balls hit to him in the course of the game. I mean, he’s a big part of our lineup right now, a big part of our offense.”

After Gattis homered for the second consecutive game Wednesday at Miami, Gonzalez mentioned the possibility of playing him at first base in Friday’s series opener against the Nationals, even though Gattis’ only pro-ball experience at the position was seven games at Class-A Rome in 2011. “I’ve done crazier things,” Gonzalez said at the time.

He wanted to keep letting veteran Gerald Laird catch rookie pitcher Julio Teheran, who started Friday’s series opener against the Nationals. But Gonzalez also wanted to keep Gattis’ hot bat in the lineup, since he was hitting .391 with three homers, six RBIs and an .826 slugging percentage in just 23 at-bats before Friday.

So with the Nationals starting a left-hander, Ross Detwiler, in the series opener, Gonzalez had Gattis take ground balls Friday afternoon and, satisfied he could handle it, penciled him in the lineup at first base.

“This is not crazy; this is not crazy at all,” Gonzalez said when reminded of his comment Wednesday. “He took ground balls. He looks fine. He’s played it before. He looked good. He’s comfortable with it, we’re comfortable with it. Go get ’em.

“If we’re winning the game late in the game or something, we can make a move, get a better defender in there, or leave him in the game and put him behind the plate and do something else someplace else, depending where the lineup falls.”

Chris Johnson, who has filled in at first base with Freddie Freeman on the disabled list, moved back to third base Friday and left-handed-hitting third baseman Juan Francisco was out of the lineup.

Gattis saw where Gonzalez mentioned the possibility after Wednesday’s game, but didn’t think he was serious.

“I didn’t think anything of it until today,” said Gattis, who took the early bus to the ballpark at 1:30 p.m. for early batting practice and to take ground balls, as requested. He didn’t know he actually was going to play first base until Gonzalez posted the lineup. Gattis said he was ready and had a simple goal.

“Do more good than bad, hopefully,” he said, smiling. “And, you know, just play baseball.”

Since those games at first base in Class-A ball in 2011, Gattis hadn’t even fielded grounders other than before one 2012 spring-training game. The 240-pound Texan said he played some first base on high school select teams and in college.

Martinez to DL: The Braves opened a roster spot for veteran reliever Luis Ayala by placing reliever Cristhian Martinez on the 15-day disabled list with what was diagnosed as a right-shoulder strain.

Manager Fredi Gonzalez said Martinez returned to Atlanta for a checkup Thursday after flying with the team to Washington from Miami late Wednesday. The Braves acquired Ayala from Baltimore in a trade earlier in the day Wednesday, and he joined the team for Friday’s series opener against the Nationals.

Anthony Varvaro pitched the final two innings of Wednesday’s 8-0 rout against the Marlins. Gonzalez said that was because Martinez wasn’t able to pitch the ninth inning after feeling soreness in his shoulder while warming up.

“We were going to pitch him in the last inning, and he threw about 10 or 12 pitches and turned around and told (bullpen coach) Eddie (Perez) that his shoulder was bothering him a little bit,” Gonzalez said. “We shut him down. Varvaro finished the game with two innings of work, and we flew Cristhian to Atlanta to see our doctor.

“He gave him the whole work-up, and we’re just going to shut him down for a little bit. They’re just calling it a shoulder strain. As far as I know right now, that’s all they’re going to do, just let him rest a little bit.”

Martinez and Varvaro are out of minor-league options and would have to clear waivers before being sent to the minors.

Etc.: Reliever Jonny Venters' wife, Viviana, gave birth to the couple's second child Friday. Walker Bradley Venters weighed 8 pounds and measured 20 inches. … The Braves had a majors-leading 1.89 ERA before Friday. The Elias Sports Bureau said that total matched the third-fewest runs allowed through the first nine games in franchise history. The 1888 Boston Braves allowed 18. the 1958 Milwaukee Braves had 16, and the 1993 Braves had the fewest, with 15.